Particles having extremely large surface area to volume ratios can exhibit unique and often surprising characteristics. In particular, nanoparticles, i.e., particles of less than about 100 nm in size, can exhibit properties including physical, electronic, optical, and catalytic properties unequaled by their macroscopic counterparts. The formation of light emitting nanoparticles is one area where this phenomenon is being taken advantage of. For instance, light emitting nano-sized particles have been proposed for use in measuring and sensing applications, in light emitting display devices, and in coherent light generation and optical gain applications, among others.
Known light emitting nanoparticles are either silicon nanoparticles or luminescent quantum dots. Silicon nanoparticles are not naturally luminescent, but can be surface treated to exhibit photoluminescence, usually via oxidation and optionally followed by addition of a secondary material to form a desired surface end group. Quantum dots are fluorescent semi-conductor or metal nanoparticles that can be passivated and/or capped to obtain the desired optical and physical characteristics. In either case, the materials and/or formation methods are usually expensive, complicated, and often suitable for forming only very small amounts of the luminescent materials. Moreover, many of the materials, for instance lead- or cadmium-containing semiconductor materials, are less than attractive for medical or biological-based applications due to possible toxicity of the materials.
What is need in the art are luminescent materials that can be formed from inexpensive, abundant starting materials and according to relatively simple, inexpensive methods. Moreover, what is need in the art are formation methods that can be scaled up to provide large quantities of the luminescent materials.